Antioxidant



Patented Aug. 22, 1933 curries STATES 1 ,923,707 iQfE I ANTIOXIDANT No Drawing.

20 Claims;

This invention relates to a new class of ageresisting compounds suitable for incorporation as antioxidants in rubber, gutta percha, balata and other deteriorable compositions. 2 1e substances 5 comprising the class in question have been found by numerous tests to protect rubber against deterioration from such influences as heat, light and oxygen. In addition they impart other desirable properties, such as improved tensile strength, to the vulcanized product.

This application is in part a continuation of application Serial. No. 347,183, filed March 14, 192 9. 7

Substances which may be employed as antioxidants in accordance with the teachings of the invention are tertiary N-dicyclic naphthylamines of the following type formula:

R being a naphthyl group, substituted or unsubsti- V tuted; R1 and R2, cyclic group's. Particularly illustrative of the cyclic groups are alicyclic radicals such as cyclo hexyl and aryl radicals such as phenyl, tolyl, xylyl and naphthyl. It is to be understood that as hereinafter used the term tri beta naphthylamine, tri alpha naphthylamine,

N-diphenyl (alpha or beta) naphthylamine, N- phenyl di (alpha or beta) naphthylamine, N-phenyl alpha beta dinaphthylamine, N-di tolyl (alpha or beta) naphthylamine, N-phenyl tolyl beta naphthylamine, N-para ethoxy phenyl tolyl 40 beta naphthylaznine, N-phenyl xylyl alphanaphthylamine, N--di-xylyl naphthylamines, N-tolyl xylyl beta naphthylamine, N-di ortho hydroxy phenyl naphthylamine, N-tolyl di (alpha or beta) naphthylamine, N-xylyl di (alpha or beta) naphthylamine, N-dicyclo hexyl naphthylamine, N- cyclo hexyl dinaphthylamine, N-c'yclohexyl phenyl beta naphthylamine. N-cy'clohexyl phenyl alpha naphthylamine, N-diphenyl tetra hydro naphthylamine, N-4-amino Z-methyl phenyl tolyl naphthylamine N-di-tolyl tetra hydro naphthylamine,

N-phenyl tolyl tetra hydro naphthylamine, N-

cyclohexyl tolyl tetra hydro naphthylamine, N-

tolyl di tetra hydro naphthylamine, N-tri tetra hydro naphthylamine, N-dipara met-boxy phenyl alpha naphthylamine, l -di-xylyl tetra hydro naphthylamine and N-para amino phenyl phenyl beta naphthylamine.

The antioxidants of the present invention, in general, may be prepared by simple chemical processes; for instance, N-diphenyl naphthyl- Application September 14, 1932 Serial No. 633,213

amine may be prepared by reacting in an autoclave 56?.grams of diphenyl amine with 216 grams of beta naphthol in the presence of about 7.2

grams of tin tetra-chloride at a temperature of approximately 346 degrees C. for 8 hours. A dark brown oil is first obtained, from whiclriby pour-.

ing into 1 /2 liters of Water containing grams of sodium hydroxide, about'43 grams of beta naphthol are recovered. The residue, a soft buttery" 4.78% nitrogen as compared with the theoretical nitrogen content of 4.74% and melts at 161.5 degrees C. The N-diphenyl alpha naphthylamine portion melts at 119-1195 degrees C. and has a nitrogen content of 4.60% as compared with-the theoretical of 4.74%. In the subsequent data tests of the mixture of the two compounds are given.

Tri beta naphthylamine may be obtained by heating beta naphthol with anhydrous ammonia in an autoclave at approximately 310 degrees C.

for a period or 8-14 hours in accordance with the disclosure of a copendin application Serial No. 274,683, filed May 2, 1928. The product, containing a large amount of dibetanaphthylamine in addition to the tri beta naphthylamine, may be separated by extraction with benzol in which the tri beta naphthylamine is readily soluble and from which it crystallizes upon standing in the form of line White crystals having a melting point of from 233 to 235 degrees C. Solutions of tri beta naphthylamine show a dark blue fluorescence when they are, held up to the light. The crystalline material itself fiuoresces a brilliant light blue when exposed to ultra violet light. In addition, it is quite soluble in aromatic hydrocarbons but comparatively insoluble in ethyl alcohol. The antioxidants of the present invention may be employed advantageously in substantially any of the standard rubber formula, the following being one in which they have been found to give excellent results:

Samples prepared in accordance with the foregoingformula were subjected tovulcanization for varying periods of time and then tested to ascertain their physical characteristics. One set from each type'of stock was tested immediately for tensile strength and elasticity. A second set was subjectedto ageing in a Bierer-Davis bomb for 6 days in oxygen at 50 degrees C. under 150 pounds per square inch pressure. At the conclusion of the 6day period the samples were re- 1 Cure Stress in kgs/cm liercent Perceirt t Wei" 1 Pressure 500 per- 100 per- 9 1 g f lbs. sq. cent cent Break w mcwase in. elong. elong..'

Tri beta naphthylamine Original 4O 12 48 109 880 50 i0 16 56 135 850 7O 2G 93 170 S00 After ageing 35 -10 1a '41 I 105 370 .21 i0 19 135 830 52 40 '27 104 152 7 5 .08

N -dipheny1 naphthyla'mine Orig incl After ageing 35 A 40 13 38 72 810 22 5O 4O 15 4G 81 800. 38 7O 40 20 70 96 7 5O 50 From the foregoing it is apparent that the compounds herein disclosed are highly suitable for antioxidants of 'rubberan'd other products which undergo deterioration unden the influences of heat, light and oxygen; Itwill'be evidentthat numerous changes may be'made in the procedure to be followed and the" chemicals'employed with out departing from the inventiveconcept. It is intended that the patentShall-covrjby suitable expression in the appended claims, hatever features of paten'table' novelty reside in the invention.

' What I claim is:

1'. A 'method of preserving rubber which comprises subjecting a vulcanizable rubber compound to vulcanization in-the presence ofatri-naphthylamine.

2. A method of preserving rubber which comprises subjecting a vulcanizable'rubber' com pound to vulcanization in the presence "of a tribetamaphthylamine,

3 A- rubber compound which has been vulcanized in the presence of a itri-naphthylamine.

4;. A rubber compound that has been vulcanized in the presence of a material having the following formula: '(CwHflsNf v 5. A rubber product that has been vulcanized in the presence ofv tri-beta naphthylamine.

' in which R and R1 are cyclic groups.

6. A method of preserving rubber which comprises subjecting it to vulcanization in the presence of a naphthylamine having the formula in which R and R1 are benzenoid groups.

8. A method of preserving rubber which comprises subjecting it to vulcanization in the presence of 'a naphthylamine having the formula in which R and R1 are cy clohexyl grpups. 9. A method of preserving rubber which comprises subjecting it to vulcanization in the presence ofa naphthylamine having the formula" r 11. A method of preserving rubber which comprises subjecting it to vulcanization in the presence of a naphthylamine having the formula ga h l in 16. A rubber product that has been vulcanized in the presence of a tertiary N-dibenzenoid naphthylamine.

' 17. A rubber product that has been vulcanized in the presence of a tertiary N-dicyclic naphthylamine. 5 Y

18. A rubber product that has been vulcanized in the presence of N-diphenylbeta naphthyl- 20. A rubber product that has been vulcanized in the presence of N-dicycloheXyl naphthylamine.

ALBERT M. CLIFFORD. 

